The subject matter disclosed herein relates generally to medical diagnostic systems, and more particularly to quantitative ultrasound (QUS) devices.
QUS devices such as ultrasonic densitometers and ultrasonometers use ultrasonic sound waves to measure bone integrity. Validation of QUS devices is an important function to ensure continued proper measurements that allow for proper diagnosis. QUS devices must remain stable for many years in order to properly assess the advancement of osteoporosis or monitor therapies. Thus, measurement parameters such as speed of sound (SOS), also referred to as time-of-flight, and broadband ultrasonic attenuation (BUA) need to be properly measured over time.
QUS phantoms are used to monitor QUS device stability. Conventional QUS phantoms use stable and well-characterized liquids such as water to attenuate signals. Other conventional QUS phantoms use a solid material such as rubber with known ultrasonic properties. Neither of these QUS phantoms satisfactorily simulates bone morphometry. Accordingly, the interaction of the acoustic wave from the QUS device and the phantom do not mimic bone, resulting in simulations that may not be particularly accurate. Additionally, liquids such as water are not very attenuative, such that the QUS device operates at minimum power. The solid phantoms also have aging effects. For example, materials with good BUA characteristics are typically rubbery. One typical material used for QUS phantoms is neoprene. As the neoprene material ages, more cross-linking between the molecules in the material occurs. This cross-linking results in a harder material and changes in the acoustic properties. The change in material hardness thereby reduces the utility of the QUS phantom for long term monitoring. Moreover, the water and solid QUS phantoms both have temperature induced drift or value changes.